Target structure for three-color cathode ray tubes or the like



Dec. 31, 1957 B. M. FELBURG 2,818,525

TARGET STRUCTURE FOR THREE-COLOR CATHODE RAY TUBES OR THE LIKE Filed Ju ly 18, 1955 GREEN ELECTRON GUN ELECTRON GUN RED ELECTRON I BUDDY M. FELBURG IN V EN TOR.

' THIS ATTORNEY Unite f TARGET STRUCTURE FOR THREE-COLOR CATHODE RAY TUBES OR THE LIKE Application July 18, 1955, Serial No. 522,539

9 Claims. (Cl. 315-21) This invention relates to target structures for three-color cathode ray tubes and, more particularly, to an improved target structure the cost of construction of which will be at a minimum, and the performance of which will be highly satisfactory. This invention is to be understood to be suitable for employment in either one gun or three gun cathode ray tubes having either conventional or aluminized face plates; in the case of three gun cathode ray tubes the electron guns may either be separated or adjacently disposed so long as the electron beam paths each have an inclined angle of incidence relative to the cath ode ray tube face plate.

In the past, several approaches have been made in de signing a satisfactory three-color cathode ray tube. One type of tube currently in use is the well known dot-sequential tube which employs a perforated shadow mask adjacent the tube target area. This type of tube has two well known disadvantages, namely, the difficulty in attaining proper registration of the shadow mask with the phosphor dot pattern and also the disadvantage of reduced tube efiiciency by virtue of the substantial interruption by the shadow mask of a large portion of the incident electron beams. Another type of three-color cathode ray tube heretofore suggested is that employing a target area consisting of a multitude of trihedrons the faces of each of which are coated with phosphors having different colors of luminescence. In this latter type of tube a unique grid work is interposed between the target area and the electron guns so that the electron beams will be made to approach normally the respective faces of each trihedron target elemental area. While the definition and line structure of this type of tube are quite satisfactory, yet the cost of manufacture of the trihedron plurality face plate is at the present time prohibitive.

Therefore, it is an object of the present invention to provide a new and useful target structure for employment in three-color cathode ray tubes.

It is a further object of the present invention to provide a new and useful target structure for employment in three-color cathode ray tubes which will be of low-cost manufacture and yet capable of producing high quality definition, good line structure, a minimum of color dilution, and general optimum performance.

According to the present invention, a three-color cathode ray tube employs a face plate the inner surface of which is provided with a plurality of three-phosphor elemental areas. Disposed upon or adjacent these elemental areas is a unitary member comprising plurality of electron beam constraining elements which are positioned normal to the tube face plate such that the edge portions thereof define the boundaries between adjacent three-phosphor elemental areas. In a preferred embodiment of the invention, the screen structure formed by the aforementioned electron beam constraining elements is charged negatively and includes sub-elements positioned similarly to the principal constraining elements to define adjacent phosphor areas within each three-phosphor elemental area.

atent Patented Dec 31, v 1

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The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in connection with the accompanying drawings, in which:

Figure l is an isometric view of a representative target area of a cathode ray tube employing the present invention.

Figure 2 is a plan view of a representative portion of the target area of a cathode ray tube in a second embodiment of the present invention.

In Figure 1, face plate 10 has upon its inner surface a plurality of geometric-figured phosphor elemental areas representative of which are red, blue, and green triangular phosphor areas 11, 12 and 13, respectively, and red, blue. and green quadrilateral phosphor elemental areas 14, 15 and 16, respectively. Wall pluralities 17, 18 and 19 are included in a unitary member and delineate the several three-color phosphor triangles 20 and 21. Each wall of wall pluralities 1'7, 18 and 19 should be of the order of .010 inch high and the sides of each triangle 20 and 21 will be of the order of .030 inch long. In the preferred embodiment of the present invention secondary wall plu ralities 22 and 23 delineate each of the three phosphor areas within each triangle 20 and 21. The height of the smaller walls which define the different colored phosphors Within each triangle should be of the order of .004 inch. The electron guns may be spaced apart or enclosed in a single glass envelope, so long as the electron paths from the red, blue and green guns approach the face plate of the cathode ray tube at a substantially uniform inclined angle of incidence. A source of negative potential, illustrated by battery 24, will be applied to the entire screen structure. The screen structure itself may be either mounted directly upon the tube face plate after the phosphor pattern is silk-screened thereon, or if the phosphored face plate is aluminized the screen structure may be disposed in a frame (not shown) adjacent to and registered with the phosphor pattern on the tube face plate.

The screen structure and face plate combination shown in Figure 1 operates as follows. The red, blue and green electron guns are removed sufiiciently from the target area so that all electron path angles of incidence relative to the cathode ray tube face plate will be substantially the same during the entire scanning interval. An electron beam emanating from the red electron gun and approaching phosphor area 11 will be precluded from impringing upon blue and green phosphor areas 15 and 16 by virtue of the interposition of wall 25 between the oncoming electron beam and phosphor areas 15 and 16. In addition, the negative charge upon wall 25, as well as u on walls 26 and 27, will tend to promote impingement in a normal direction by the oncoming red electron beam upon red phosphor area 11. The impingement of the electron beams from the blue and green electron guns will be affected similarly by wall pluralities 19 and 17 for all intervals of scan so that the electron beams from such electron guns will be able to impinge only the blue and green phosphor elemental areas, respectively. Again, the negatively charged secondary walls dividing each of the phosphor areas within each three-phosphor triangle will tend to promote normal impingement by the oncoming electron beam.

If cost of construction so dictates, it may be desirable to eliminate the secondary walls from the screen structure. However, by such a practice, color definition may be sacrificed somewhat.

conceivably, the intermediate walls may be eliminated and Wall pluralities 17, 18 and 19 may constitute a plurality of crystal or nickel walls, or walls composed of other substances, which are characterized by electron reflective properties. In such a case, the screen structure will not be charged by a negative voltage. But again, some color definition will be sacrificed by the omission of the lower inner walls defining each. phosphor area within each three-phosphor triangle.

The screen structure and phosphored face plate shown in Figure 2 is identical to that of Figure 1 with the exception that tri-color phosphor dots are employed in each three-color triangle instead of the different colored triangular and quadrilateral elemental areas shown in Figure 1. Silk-screening the phosphor dot pattern of Figure 2 may prove easier to perform, perhaps, than in the case of the phosphor pattern of Figure l.

The screen structure and face plate phosphor configuration of Figure 2 operates substantially the same as the structure of Figure 1.

While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects, and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

I claim:

1. A target structure for a three-color cathode ray tube including, in combination, a face plate having a plurality of three-phosphor triangular areas, and a unitary member comprising a plurality of major wall elements delineating said triangular areas, said wall elements each being disposed normal to and in proximate relation with said face plate.

2. Apparatus according to claim 1 in which said major wall elements are charged negatively.

3. Apparatus according to claim 1 in which said wall elements exhibit electron reflective properties.

4. Apparatus according to claim 1 in which a plurality of minor wall elements are also included in said unitary member and delineate each elemental phosphor area within each of said three-phosphor triangular areas, the height of said minor wall elements being less than the height of said major wall elements, said minor wall elements likewise being disposed normal to and in proximate relation with said face plate.

5. Apparatus according to claim 2 in which a plurality of minor Wall elements are also included in said unitary member and delineate each elemental phosphor area within each of said three-phosphor triangular areas, the height of said minor wall elements being less than the height of said major wall elements, said minor wall elements being disposed normal to and in proximate relation with said face plate, said minor wall elements also being charged negatively.

6. Apparatus according to claim 4 in which the elemental phosphor areas of a first representative three-phosphor triangular area have a triangular configuration and the elemental phosphor areas of a second representative three-phosphor triangular area adjacent said: first threephosphor triangular area have a quadrilateral configuration.

' 7. Apparatus according to claim 5 in which the elemental phosphor areas of a first representative threephosphor triangular area have a triangular configuration and the elemental phosphor areas of a second representative three-phosphor triangular area adjacent said first three-phosphor triangular area have a quadrilateral configuration.

8. Apparatus according to claim 4 in which the elemental phosphor areas of a first representative threephosphor triangular area have a circular configuration and the elemental phosphor areas of a second representative three-phosphor triangular area adjacent said first threephosphor triangular area have a circular configuration.

9. Apparatus according to claim 5 in which the elemental phosphor areas of a first representative three-phosphor triangular area have a circular configuration and the elemental phosphor areas of a second representative threephosphor triangular area adjacent said first three-phosphor triangular area have a circular configuration.

References Cited in the file of this patent UNITED STATES PATENTS Goldsmith Mar. 3, 1953 

